At least 28 Pakistani pilgrims en route to Iraq for an Islamic religious ritual were killed as their bus crashed in central Iran, state media reported early Wednesday.

"A bus carrying Pakistani pilgrims overturned and caught fire in front of Dehshir-Taft checkpoint in the central province of Yazd on Tuesday night," state TV reported.

"28 people have been killed and 23 injured so far with the possibility of death toll increasing," it added.